Smoke from home fuels tied to emphysema

NEW YORK (Reuters Health) - People who burn wood or other “biofuels” for heat or cooking may have a heightened risk of emphysema and related lung conditions, a new study suggests.

Two men smoke on a university campus in Pingtung County, southern Taiwan, January 13, 2010. REUTERS/Pichi Chuang

In an analysis of 15 international studies, researchers found that people exposed to smoke from “biomass” fuels in their homes generally had a greater risk of chronic obstructive pulmonary disease (COPD) than those who used other sources for cooking and heating.

Biomass refers to biological materials that can be burned for energy, including wood, crops and animal dung. They are major sources of energy in the developing world, and are thought to be used for cooking and heating in half of homes worldwide.

Cigarette smoking is the primary risk factor for COPD, a group of serious lung diseases that includes emphysema and chronic bronchitis. But the role, if any, for smoke from wood and other forms of biomass has been unclear.

These latest findings strengthen the evidence that exposure to biomass smoke is a risk factor for COPD, according to the researchers, led by Dr. Pixin Ran of Guangzhou Medical University in Guangzhou, China.

For the study, published in the journal Chest, Ran’s team combined the results of 15 studies from Asia, South America, Mexico and Spain involving a total of 3,719 adults with COPD and nearly 39,000 healthy men and women.

The studies compared COPD patients with healthy individuals, surveying them about, among other things, their past exposure to biomass smoke at home. Such studies cannot prove cause-and-effect, but can only show whether there is a relationship between the variables being measured -- in this case, biomass smoke exposure and COPD risk.

Across the studies, the researchers found, participants who reported exposure to biomass smoke at home were more than twice as likely to have COPD as those with no such exposure. The risks were similar in men and women and across geographical regions.

Biomass smoke also seemed to affect COPD risk independent of cigarette smoking, possibly exacerbating the ill effects of cigarettes. Among non-smokers, Ran’s team found, exposure to biomass smoke was linked to a 2.5-fold increase in the risk of COPD. Smokers exposed to biomass smoke, meanwhile, had a more than four-fold greater risk of COPD than non-smokers who did not burn biomass fuels at home.

Given the widespread use of biomass fuels, particularly in rural areas of developing countries, Ran’s team writes, “the public health consequences of biomass smoke with regard to COPD (are) important.”

The findings suggest that efforts to reduce people’s exposure to such smoke might help prevent some cases of the lung diseases, the researchers conclude.

SOURCE: Chest, online February 5, 2010.